Diet composition of omnivorous Mesopotamian spiny‐tailed lizards (Saara loricata) in arid human‐altered landscapes of Southwest Iran

Abstract The Mesopotamian spiny‐tailed lizard, Saara loricata, is one of the largest lizard species in the Middle East. Here, we report on the diet of the lizard and their potential role in seed dispersal in Southwestern Iran. We analyzed lizard fecal pellet groups (n = 124) for their food item composition and seed content. We calculated the relative frequency of occurrence (FO%), relative volume (V%), and importance value (IV%) for each food item. Moreover, the number of seeds of each plant food item was counted. Our findings reveal the first solid evidence of omnivorous behavior in the lizard. In total, 16 plant food items and 14 animal food items were identified. Herbaceous plants (IV = 110.2%) and invertebrates (4.8%) were the most important food groups. The plant food items with the highest FO% were Poaceae (56.4%), Centaurea sp. (43.5%), and Medicago polymorpha (27.4%); and the V% for these items were 53.6%, 30.9%, and 13.1%, respectively. Most of the seeds that were consumed by lizards were from Poaceae (547 seeds; 47.81%) and Fabaceae (285 seeds; 24.91%). We also found that each individual lizard could play an equal role in the seed dispersal of all plant families identified. Previous studies show that plant species density and richness are important features for the burrow site selection of Mesopotamian spiny‐tailed lizard. This study highlights the potential role of lizards in influencing the vegetation communities around their burrows through seed dispersal.

Lizards are important seed dispersers (Valido & Olesen, 2019). In fact, lizards have been shown to be even more effective than birds for dispersing seeds in some plant communities, especially on islands (e.g., Galápagos and Canary Islands) where other seed dispersers have disappeared or experienced significant population declines (González-Castro et al., 2015;Heleno et al., 2013). Lizards are the earliest mutualistic vertebrates with plants since the Paolozoic Era (541-251 million years ago) and play an important role in seed dispersal (Tiffney, 2004;Willson et al., 1996). Lizards are often opportunistic animals in their foraging behavior (Griffiths & Christian, 1996) and the larger species and generalist lizards eat more fruits and more seeds and have greater potential for seed dispersal (Miranda, 2017;Valencia-Aguilar et al., 2013;Valido & Olesen, 2019).
In this study, we examined the diet of the Mesopotamian lizard in Southwestern Iran to determine whether they have an herbivorous or omnivorous diet. Moreover, it is important to study the feeding behavior of Mesopotamian lizards in Iran because their habitat has a high degree of human disturbance which may impact their diet. For example, about 20%-30% of areas in Western-Southwestern Iran are suitable habitats for Mesopotamian lizards (Kafash et al., 2016;Rastegar-Pouyani & Fathinia, 2015); however, these areas are mostly degraded and fragmented by human activities (e.g., overgrazing, cultivation, and oil mulching) (Elhaeesahar & Masoudi, 2018;Ghaedi et al., 2021;Mohammad Rahimi et al., 2019). Furthermore, the Mesopotamian lizards may provide important ecological benefits in the region through seed dispersal; however, we need a better understanding of whether the lizards may act as seed dispersers of native vegetation and which species of plants are likely to be dispersed.
Thus, our study of the Mesopotamian lizard's diet, and knowledge regarding their potential role in seed dispersal, is important for the rehabilitation of their habitat. In this study, our aims were as follows: (a) to study the diet composition of the Mesopotamian lizard in Iran using fecal pellet analysis to determine whether they are herbivorous or omnivorous; (b) to measure whether and to what extent Mesopotamian lizards have the potential to disperse seeds of various plant species consumed; and (c) to determine whether the number of seeds ingested varies among individuals.

| Study area
We conducted our study across three provinces in Southwestern

| Study design
We located our sampling areas based on the occurrence of the Mesopotamian lizard, these areas lie mainly around croplands ( Figure 1, Nazari-Serenjeh & Torki, 2017). In each sampling site, we searched for burrows of the Mesopotamian lizards. To ensure independent sampling of individual lizards, we retained approximately ≥100 meters distance between lizard burrows. This distance was taken from the average home range (1 to 5 hectares) of similar species such as the North-African spiny-tailed lizards, Uromastyx acanthinura (Chiraz, 2021). We selected 24 sites (24 burrow sites of 24 individuals).

| Field and laboratory work
From May to July 2016, we collected fresh (approximately 1-week-old) fecal pellet groups (several pellets together) around each lizard burrow (a distance of 10 m from each burrow) and stored them in plastic bags. In the laboratory, we counted the number of pellets in each pellet group for each individual lizard and measured the diameter and the length of each pellet separately by caliper. We also calculated the dry weight of each pellet using a digital scale.
Finally, we counted the number of pellets in each pellet group. We soaked the pellet groups in water for approximately 20-40 min. We then removed the pellets and placed them in water inside a petri dish and separated food items using tweezers under a Nikon stereo microscope. We divided food items into two groups: animal and plant food items. We identified the consumed food items to the lowest taxa using identification keys wherever possible. Within the animal food category, we further categorized food items as vertebrates and invertebrates. Likewise, items in the plant food category were further categorized as being cultivated trees, wild fruits, herbs, shrubs, and crops. We counted the seeds of the grasses, herbs, shrubs, and fruits in each pellet group.

| Statistical analysis
We calculated the relative frequency of occurrence (FO%) of the food items in each pellet group (Ghadirian et al., 2017;Soofi et al., 2017): Next, we measured the volumetric percentage of the identified food items as two-thirds (66.6%), half (50%), one-third (33.3%), one-fourth (25%), and trace (≤1%). The measured volume of each food item in each pellet group was placed into six groups for estimating mean volume: trace (≤1%), 1%-25%, 25%-50%, 50%-75%, 75%-100%, and 100%. The mean point of each volumetric group was used to calculate the overall percentage of the identified food items in the pellets (Ghadirian et al., 2017;Soofi et al., 2017). Furthermore, we calculated the relative volume (V%) of the identified food items in the pellets. In addition, we calculated the importance value (IV%; an estimate of the importance of consumed foods) of the food items/ groups estimated (Ghadirian et al., 2017;Soofi et al., 2017): where, item i is the specific consumed food item and pellet group j is the specific pellet group. To compare the difference in the mean ranks of the food groups consumed by lizards, we ran a Dunn's test, which applies a Kruskal-Wallis rank-sum test for stochastic dominance among multiple groups (Dinno, 2017). The mean ranks between different lizard individuals and the seed dispersal of different plant families were compared using Tukey honest test (Dytham, 2011).
F I G U R E 1 Sampling site locations of fecal pellet groups of Mesopotamian spiny-tailed lizard, Saara loricata, in Iran.

| RE SULTS
Overall, our sampling led to the collection of 440 pellets in 124 pellet groups. The mean number of fecal pellet groups per lizard was 5.16 ± 6.48 SD (range 1-31). The mean number of fecal pellets in each pellet group was 3.7 ± 2.4 SD (range 1-13) and the mean weight (g) of the pellet groups was 1.1 ± 1.0 SD (range 0.11-5.87).
Furthermore, the mean number of food items in each pellet group was 2.4 ± 1.3 SD (range 1-7), and the food items consumed by the individual lizards ranged between 1 and 11 items (Table S1).
We  Table 3). The average number of seeds ingested by each individual was 47.6 ± 12.9 SE (range 0-249); only four pellet groups, belonging to three individuals, did not contain seeds. The comparison of ingested seed rates among individual lizards showed that only two individuals ("S" and "D") were significantly different (p ≤ .01). In fact, the number and variety of seeds ingested by individual S and individual D were more than the other individuals (Table S1, Figure 3).
The seeds of Arecaceae were consumed significantly less than other plant families (Figure 4, Tables S2 and S3).

| DISCUSS ION
In this study, we have demonstrated that S. loricata has an omnivorous diet in southwestern Iran. In the past, however, the lizard was thought to be herbivorous. The percent of plant material in the pellets of the Mesopotamian spiny-tailed lizards was higher than animalbased food items, but pellet groups that contained exclusively plant material were lower than that reported for the Egyptian spiny-tailed lizard U. aegyptia (Castilla et al., 2011;Cunningham, 2000Cunningham, , 2001. Only, two seeds of date palm (Arecaceae; 0.17% of total seeds) were found in two pellet groups, which is similar to the findings of   Note: Here, FO%, V%, and IV% are the frequency of occurrence of items, volume percent of items, and importance value of items, respectively. TA B L E 2 Food items identified (animal and plant food items) in fecal pellet groups (n = 124) collected from Southwestern Iran, May-July 2016.  (Hatt, 1959;Soofi et al., 2022). Based on the seeds excreted by the Mesopotamian lizard, this species has the potential to be a seed disperser, which may be especially important in human-altered habitats (e.g., overgrazed pastures) in the absence of mammalian herbivores.
In light of our study findings that the Mesopotamian lizard has the potential to be an important seed disperser in Southwestern Iran, we suggest that future research should be undertaken to evaluate its actual role in seed dispersal. For example, further research on the survival, germination, dispersal distance of excreted seeds, and seedling establishment should be conducted for a better understanding of this species' role in seed dispersal in arid environments.
Furthermore, it would be interesting to examine seed dispersal by other species to determine to what extent the lizards provide this ecosystem service relative to other species.

ACK N OWLED G M ENTS
We are grateful to A. Abdoli (Shahid Beheshti University) for providing the laboratory facilities. We also thank the rangers of Bushehr, Khuzestan, and Ilam provinces for their help in fieldwork, and M.
Soofi for advice on statistical analysis and edits of the manuscript.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that supports the findings of this study are available in the supplementary material of this article.